Vehicle Motion Control Under ABS and Anti-Skid Force Limits
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Solution Overview
Problem
Existing vehicle motion control systems face challenges in managing longitudinal force effectively, leading to excessive control amounts and increased time for actual acceleration to converge to target acceleration, especially when requests exceed the controllable range.
Innovation Solution
A vehicle motion controller that automatically adjusts traveling speed based on driver assistance requests, utilizing feedback control to calculate a control amount that reduces the difference between target and actual acceleration, and limits control adjustments based on the availability of longitudinal force generated by the actuator.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If feedback control is continued when the requested longitudinal force exceeds the controllable range, then the control system attempts to eliminate the acceleration difference, but the control amount excessively increases or decreases without achieving the target acceleration
Solution Approach 1:
The system performs preliminary checking of the availability (controllable range) of longitudinal force before executing feedback control. By obtaining the maximum and minimum values of the controllable range in advance and comparing the requested longitudinal force against these limits, the system prevents excessive control amount adjustments before they occur, ensuring stable control operation.
2Productivity
If the feedback control does not consider the controllable range of longitudinal force, then the control algorithm remains simple, but the time for actual acceleration to converge to target acceleration increases
Solution Approach 1:
The system obtains the availability (controllable range) of longitudinal force in advance through an obtaining unit that retrieves maximum and minimum values from storage. This preliminary preparation enables the feedback control to quickly determine whether the requested force is achievable, allowing rapid adjustment of control amounts and accelerating convergence without adding complex control algorithms.
Solution Approach 2:
The system implements feedback control that incorporates availability information by comparing the requested longitudinal force with the controllable range limits. When the requested force exceeds the range, the system provides feedback to adjust the control amount appropriately, enabling the actual acceleration to converge to the target acceleration within the achievable range while maintaining responsive control.
3Speed
If the control amount is not limited by the availability of longitudinal force, then the control response is fast, but the control amount excessively increases or decreases when the request exceeds the controllable range
Solution Approach 1:
The system determines the controllable range (availability) of longitudinal force in advance and stores the maximum and minimum values. This preliminary determination allows the control system to quickly compare requested forces against achievable limits and adjust control amounts appropriately, maintaining fast response while preventing excessive control adjustments.
Solution Approach 2:
The system changes the control amount parameters based on the availability of longitudinal force. When the requested longitudinal force exceeds the controllable range, the control amount is adjusted to match the maximum or minimum achievable force, ensuring that control responses remain fast and accurate within the physical capabilities of the actuator.
Data Source
AI summary
A vehicle motion controller includes a feedback controlling unit that executes feedback control in which a difference between a target acceleration corresponding to a request value from a driver assistance device and an actual acceleration of a vehicle is an input, thereby calculating a control amount used to reduce the difference, a request outputting unit that calculates a request longitudinal force based on the control amount, the request longitudinal force controlling an actuator, and an obtaining unit that obtains, as information that indicates availability, information indicating whether the at least one of the anti-lock brake control or the anti-skid control is executed, the availability being a controllable range of the longitudinal force. The feedback controlling unit keeps the control amount constant when the at least one of the anti-lock brake control or the anti-skid control is executed.